At present, in a thin film transistor (TFT) of a liquid crystal display, silicon, for example, amorphous silicon or polysilicon, usually acts as a main component of an active layer. For a TFT using the amorphous silicon as an active layer (hereinafter, referred to as an amorphous silicon TFT), as limited by features of the amorphous silicon such as mobility and on-state current, etc., it is difficult to be used in situations requiring a larger current and a faster response, for example, an organic light emitting display and a display with a large size, a high resolution and a high-refresh frequency, and the like. On the other hand, for a TFT using the polysilicon as the active layer (hereinafter, referred to as a polysilicon TFT), although it may be used in situations requiring the large current and the faster response as features of polysilicon is superior to that of the amorphous silicon, it is difficult to be used for manufacturing a panel with a medium or large size due to a poor homogeneity of the polysilicon. Therefore, a TFT using an oxide semiconductor as the active layer (hereinafter, referred to as an oxide TFT) gains more and more attention.
For the oxide TFT using the oxide semiconductor, for example, indium gallium zinc oxide (IGZO) and indium tin zinc oxide (ITZO), as the active layer, the mobility, on-state current, switching characteristic and the like are superior to that of the amorphous silicon TFT. Additionally, although the features of the oxide TFT are not as good as that of the polysilicon TFT, the oxide TFT is still good enough for applications requiring the larger current and the faster response. Moreover, as the oxide semiconductor has a good homogeneity, thus it has no problem relating to the homogeneity comparing with the polysilicon, then the active layer may be manufactured via sputtering, deposition, and the like, accordingly there is no need to add an additional device and the cost is low.
FIG. 1 is a structural representation of an oxide TFT array substrate in the prior art. As shown in FIG. 1, the oxide TFT array substrate includes an oxide TFT 1 and a pixel electrode 7, in which the oxide TFT 1 includes a gate electrode 2, a source electrode 3, a drain electrode 4 and an oxide active layer pattern 5, in which the source electrode 3 and the drain electrode 4 are located above the oxide active layer pattern 5, and the drain electrode 4 is connected with the pixel electrode 7. During a process for manufacturing an oxide TFT array substrate, the source electrode 3 and the drain electrode 4 are usually formed by etching a source/drain metal layer (not shown in drawings) using a wet process. As an etching solution may also etch the oxide active layer pattern 5 located below the source/drain metal layer, the oxide active layer pattern 5 will be destroyed thereby. In order to solve the above problem, in the prior art, an etch stopping layer 20 is manufactured on the oxide active layer pattern 5 except for regions where the oxide active layer pattern 5 is arranged in such a manner so as to be in contact with the source electrode 3 and the drain electrode 4, so that the oxide active layer pattern 5 is protected from being destroyed. However, this requires adding at least one photoetching process, which makes the current process for manufacturing an oxide TFT array substrate basically require 6 to 7 photoetching processes. As a result, the production cost will be increased.